At a time when so many indicators of social and economic inequality paint a grim picture of the state of the American dream, a new NBER paper by the Princeton economists Janet Currie and Hannes Schwandt provides a rare cause for optimism: The mortality gap between rich and poor children narrowed considerably between 1990 and 2010.

A number of highly-publicized earlier studies have shown an increasing correlation between wealth and mortality among the middle-aged and elderly, but the new findings suggest that death rates in later generations will be more egalitarian:

Among adults age 50 and over, mortality has declined more quickly in richer areas than in poorer ones, resulting in increased inequality in mortality. This finding is consistent with previous research on the subject. However, among children, mortality has been falling more quickly in poorer areas with the result that inequality in mortality has fallen substantially over time. This is an important result given the growing literature showing that good health in childhood predicts better health in adulthood. Hence, today’s children are likely to face considerably less inequality in mortality as they age than current adults.

The authors point out that their findings complicate the straightforward materialist explanation favored by some left-wing observers of mortality trends: that the gap could be closed through income redistribution alone. “The fact that inequality in mortality has been moving in opposite directions for the young and the old,” the paper says, “argues against a single driver of trends in mortality inequality, such as rising income inequality.”

So what accounts for the convergence? The most important factor, they speculate, is “a strong improvement in health behavior,” reflected in falling rates of smoking and obesity, “which simply occurred with some lag among the poor” (suggesting that the current elevated rates of mortality among older poor and working class people may be a transitory phenomenon). But regardless of the underlying cause of the trend, the paper highlights the fact that—despite the prevailing mood of the country today—things just might be better tomorrow.